A valve device for controlled supply of a pressure fluid. The invention relates to a valve device for controlled supply of a pressure fluid, comprising a housing having a supply chamber for the supply of a pressure fluid from an inlet connected to a pressure fluid source, and having an outlet communicating with the supply camber via an outlet valve.
The present valve device in the first place has been developed with the view of functioning as a breathing-controlled valve which is to give persons having a lung failure a contribution of oxygen.
A considerable number of persons having a lung failure are dependent on their breathing air being enriched with oxygen. This primarily takes place in that the patients are equipped with a portable pressure reservoir and are supplied with oxygen via a nose catheter. In most cases the oxygen is supplied as a continuous flow, and the patient consequently misses the oxygen quantity supplied during the time in which the patient himself does not inhale. In practice this implies that approximately ⅔ of the supplied oxygen is lost. In addition, the constant gas flow into the nostrils will be unpleasant to most people because the mucous membranes of the nose become dry and irritated. On a global basis there is a very large number of persons which receive a supply of oxygen from a portable reservoir (approximately 800,000 in the U.S.). The yearly costs of oxygen to the individual patient is of the order of NOK 100,000,. Thus, one can achieve large savings by minimising the oxygen loss.
Today, there are delivered electronic oxygen savers which are able to record the starting time for each inhalation, and which also provide for a metered supply of oxygen. These are based on electronic pressure sensors, and are constructed to deliver oxygen in a certain (adjustable) time interval after that start of inhalation has been recorded. Thus, if the patient has an irregular breathing pattern, one will constantly run the risk that a part of the supplied oxygen never arrives at the lungs of the user. The drawback of these oxygen savers is that the batteries must be changed relatively often, and that they are complicated and expensive. So far, these have not been a success in the market.
An oxygen saver should have a quick response and, ideally, should deliver oxygen only as long as the patient inhales. This implies that the oxygen saver must be able to register the pressure in the breathing passages of the patient independently of whether the oxygen saver delivers oxygen or not. In addition, if the oxygen saver is to be able to be based on a pure mechanical regulation of the oxygen flow, the control device for the oxygen supply must be so sensitive that it can be controlled by the small pressure forces which will be generated in the nose catheter by the respiration of the patient.